Synthesis gas may be defined as any of several gaseous mixtures used for synthesizing a wide range of compounds, both organic and inorganic. Such mixtures result from reacting carbon-rich substances with steam (steam reforming) or steam and oxygen (partial oxidation). These mixtures contain chiefly carbon monoxide and hydrogen, and usually low percentages of carbon dioxide and nitrogen (less than 2%). The organic source materials may be natural gas, methane, naphtha, heavy petroleum oils or coke. The reactions are usually nickel-catalyzed steam-cracking (reforming) of methane or natural gas (CH.sub.4 +H.sub.2 O--CO+3H.sub.2); partial oxidation of methane, naphtha, or heavy oils; and (especially in view of the petroleum shortage) the water-gas reaction with coke (C+H.sub.2 O--CO+H.sub.2).
It is known to use transition-metal catalysts to convert synthesis gas to alcohols, aldehydes, acetic acid, etc. A continuing problem exists, however, in finding suitable catalysts for selectively converting synthesis gas to alcohol mixtures.
U.S. Pat. No. 2,061,470 discloses the production of methanol and other carbon compounds by contacting a gaseous mixture containing carbon monoxide and hydrogen under pressure with a catalyst consisting of the reduction product of a fused mixture of copper oxide and manganese oxide, or copper oxide and zinc oxide, and an oxide of an element selected from the group consisting of chromium, vanadium, zirconium, aluminum, magnesium, titanium, thorium, silicon and cerium.
U.S. Pat. No. 4,298,354 discloses an oxide-complex catalyst containing copper, thorium, an alkali metal and at least one other metal selected from the group consisting of Ca, Mo, Rh, Mn, Pt, Ce, Cr, Zn, Al, Ti, La, V, U, Ru, Re and Pd. These catalysts are useful in converting synthesis gas to alcohols, such alcohols containing from 2 to 6 carbon atoms and normally not more than 85% methanol by weight.
U.S. Pat. No. 4,377,643 discloses the production of alkanes and oxygenated hydrocarbons, particularly alcohols, from synthesis gas using a catalytic complex containing ruthenium, copper, an alkali metal and a promoter selected from the group consisting of Rh, Ir, Pd and Pt.
There is a continuing need for a suitable catalytic complex for converting mixtures of hydrogen and carbon monoxide, particularly synthesis gas, to alcohol mixtures.